Intracellular supravital stain delocalization as an assay for antibody-dependent complement-mediated cell damage.

The ability of hamster SV40 tumor cells to concentrate Neutral Red into localized intracytoplasmic vacuoles and granules has been correlated with the ability of those cells to adhere and to replicate in tissue culture. Cells damaged by complement-fixing anti-tumor antibody and metabolic inhibitors first undergo delocalization of the dye, which appears as a diffuse stain throughout the nucleus and cytoplasm. More severely damaged cells lose the stain entirely, at a stage of progressive cell damage correlated with Trypan Blue uptake. A rapid and sensitive cytotoxic assay procedure has been based upon Neutral Red staining behavior, and the assay has been used to study antibody-dependent, complement-mediated cytotoxic anti-SV40 tumor activity in the sera of normal hamsters.